1. Field of the Invention
The present invention generally relates to a solid electrolytic capacitor, in particular, to a solid electrolytic capacitor having a lead frame that can easily orient capacitor elements and a lower equivalent series resistance.
2. Description of Related Art
Because solid electrolytic capacitor has the advantages of small size, large capacitance and good frequency characteristic, it can be used as a decoupling element in the power circuit of a central processing unit (CPU). In general, a plurality of capacitor elements is stacked together to form a solid electrolytic capacitor with a high capacitance.
FIG. 1 is a schematic cross-sectional view of a conventional solid electrolytic capacitor. Referring to FIG. 1, the solid electrolytic capacitor 100 includes a plurality of capacitor elements 110 and a lead frame 120. Each capacitor element 110 includes an anode part 112, a cathode part 114 and an insulating part 116. The insulating part 116 electrically insulates the anode part 112 and the cathode part 114 from each other. More specifically, the cathode parts 114 of the capacitor elements 110 are stacked over one another. Furthermore, conductive layers 130 are disposed between adjacent capacitor elements 110 so that the capacitor elements 110 are electrically connected to one another.
Referring to FIG. 1 again, the lead frame 120 has an anode terminal part 122 and a cathode terminal part 124. The anode parts 112 of the capacitor elements 110 are electrically connected to the anode terminal part 122 while the cathode parts 114 of the capacitor elements 110 are electrically connected to the cathode terminal part 124.
In the solid electrolytic capacitor 100 shown in FIG. 1, the capacitor elements 110 are connected through the conductive layers 130. Therefore, in the process of stacking the capacitor elements 110, accurately aligning each capacitor element 110 is a problem and leads to a low process yield of the solid electrolytic capacitor 100. Moreover, the following problems are often encountered in welding several anode parts 112 of a conventional solid electrolytic capacitor 100.
FIG. 2 is a schematic cross-sectional view showing a conventional process of welding several anode parts of a stack of capacitor elements. FIG. 3 is a top view showing a conventional process of welding the anode parts of a stack of capacitor elements together. Referring to FIG. 2 and FIG. 3, a spot welding apparatus 140 is used to weld the anode parts 112 together after the capacitor elements 110 are stacked over one another. After the spot welding apparatus 140 has applied a stress 160 to a welding spot 150, the stress 160 will spread out. Because the anode parts 112 and the cathode parts 114 have different thickness, uneven stress distribution between the anode parts 112 and the cathode parts 114 may develop and ultimately may lead to the generation of a crack 170. Consequently, the process yield of the process of welding the anode parts 112 together is decreased.